The final goal of this reseach is to get the height profile of Mars atmosphere and ionosphere by receiving the S and X band coherent-nonmodulated radio waves originally generated by using an ultra-stable oscillator onboard Japan's first Mars orbiter.The height profile of the atmosphere and ionosphere allows us to study the dynamics of Mars atmosphere (weather), the interaction between neutral/ionized atmosphere and solar wind, the interaction between ionosphere and thermosphere and effect of dust storm on the both atmospheres. For this purpose, we need 1) to reduce the frequency of the received S and X band signals which are radiated from the spacecraft transmitters down to 20 kHz so that we can more easily calculate the deviation of the frequency, 2) to digitize the down converted video signals in order to conduct computer analysis, 3) detection of the frequency deviation due to the atmosphere/ionosphere of Mars, and 4) convertion of the frequency deviation to the height profile of th
… Moree atmosphere/ionosphere density.The grant-in-aid we received allowed us to complete the works listed above as item 1) and 2). Specification of the system to convert the frequency down to 20 kHz and to digitize the signal was discussed by ISAS and a private company in the several meetings and summarized as a final report. The hardware system was manufactured according to the specification and the softwares to store the digitized signal in the memory devices were also completed by the end of 1998.Unmodulated S band signal from the spacecraft was received in February and the performance of the data acquisition system was confirmed for S band system. X band signal will be received on the 13th and 14th of April and the performance will be examined.Next goalOur future targets are the item 3) and 4) and a part of these activities is now under way. In January, 2001, we are going to conduct a solar conjunction experiment, in 2003, we will try to detect the moon photoelectron layer, and finally in 2004, Mars atmosphere/ionosphere will be investigated. Less